Data that can be read and understood without any special measures is called plaintext or clear text. Disguising plaintext in such a way as to hide its substance is called encryption. Encrypting plaintext results in unreadable gibberish called cipher-text. A message may be encrypted to ensure that information in the message is hidden from anyone for whom it is not intended, even those who can see the encrypted data. In order for the intended recipient to be able to eventually read the message, the encrypted message is decrypted.
Pretty Good Privacy (PGP) encryption allows for securing communications end to end, but suffers from the problem that public keys for all recipients need to be known. This may be a problem in cases where the source of the message might not know all recipients, such as public distribution lists. The recipients can share a private key, but then access may not be easily revoked without revoking the private from everyone.